Originally posted by madisonears
I wish some other builders would share their experiences with and impressions of these amps. Over a hundred kits went out, and so far most entries here are about problems, not pleasures.

I soldered up a pair of boards last weekend and everything went fine. The excellent components labelling along with the detailed printing on the boards made it pretty tough to get anything wrong.
Within a few hours they were playing and sounding good. No hum.
Once I get them in a proper case, I'll post a pic. Right now they are on a breadboard aka 2x6 chunk.
Thanks again to Peter and Uriah.

Let me preface these observations by suggesting that anyone who is tired of my ramblings and ruminations on this topic is welcome to skip this post and advise me that I'm going on too long about nothing of importance. However, I feel this information is vital to anyone seeking, as I am, ultimate performance from this unique and elegant design, and I enjoy writing about my experience and impressions.

Additionally, let me say that I am not an inveterate tweaker. I have never popped the top of any component and grabbed my iron to start disemboweling some perfectly functioning piece of equipment. I built the original Dynakits back in the 70's with modest success, but, since then, my only forays into the world of DIY involved building cables (very worthwhile, by the way), speakers, and a couple of truly crappy LM1875 amp kits.

I have now made the following mods to both of my monoblocks: substituted AudioCap Theta's for C13; substituted WIMA MKP's for C21; and substituted ELNA Silmic II's for C9. So far, the amps have changed from very average solid state to superb solid state. I have heard lots of very good to excellent SS and tube amps in my system, and these are now close to being the best SS I have ever heard, rivals to the BAT VK-60 monoblocks I once had here. (I sold those because they were impractical beasts, consuming gobs of electricity and converting most of it into unbearable heat and some of it into sublime sound. I tired of fiddling with tubes and not being able to listen to music when the ambient temperature exceeded 80 degrees because my non-air conditioned living room became an oven.)

With this latest modification of C9 and C21, these amps now produce substantial and musical bass, extending very low, with almost the same control as my ARC 100.2. The mids are clearer and more musical, with beautiful tonality and depth. The highs are open and smooth, with plenty of air, extension, and detail and no harshness whatsoever. Images float freely but firmly in real space.

I will write here what some readers might feel is heresy: Mauro was wrong about one thing. In one of his earlier posts on the original MyRef thread, I believe he stated that this amplifier design was not sensitive to quality of components. If that is what he wrote or meant, he was absolutely wrong on that count. He never did divulge what type of components he used to build his own amps. I can state unequivocally that the components supplied in this current round of kits, at least at these critical points, is below the quality required to achieve ultimate performance. Peter and Uriah did an excellent job, and I will always be grateful for their considerable efforts to make this amp available again and do such a thorough job of organizing the kits. However, I believe their goal of holding to a price point by selecting inexpensive and merely adequate parts, while admirable, was somewhat misguided. They probably felt, as Mauro himself stated, that any parts within spec would be suitable. I'm sure they felt that anyone who wanted to could upgrade parts, and my point is that everyone who bought these kits should not hesitate to do just that. These are $65 amplifiers as supplied, but they gain in value completely out of proportion to the cost of a few simple improvements.

Today I received my Mundorf caps (they cost as much as the kits!) and PRP resistors (cheap), so steel yourselves for more preaching after these parts are incorporated into my amps.

I'm sure they felt that anyone who wanted to could upgrade parts,
Less to control costs and more to do this.
We stuck with the BOM and let it be affordable to all. A 50 cent cap makes it affordable to all and an AudioCap Theta by itself would probably have taken away the affordability.
I bought some BlackGates yesterday by the way. I know caps count
Uriah

Originally posted by madisonears I have now made the following mods to both of my monoblocks: substituted AudioCap Theta's for C13; substituted WIMA MKP's for C21; and substituted ELNA Silmic II's for C9. So far, the amps have changed from very average solid state to superb solid state. I have heard lots of very good to excellent SS and tube amps in my system, and these are now close to being the best SS I have ever heard, rivals to the BAT VK-60 monoblocks I once had here.
...
With this latest modification of C9 and C21, these amps now produce substantial and musical bass, extending very low, with almost the same control as my ARC 100.2. The mids are clearer and more musical, with beautiful tonality and depth. The highs are open and smooth, with plenty of air, extension, and detail and no harshness whatsoever. Images float freely but firmly in real space.
...
I will write here what some readers might feel is heresy: Mauro was wrong about one thing. In one of his earlier posts on the original MyRef thread, I believe he stated that this amplifier design was not sensitive to quality of components. If that is what he wrote or meant, he was absolutely wrong on that count. He never did divulge what type of components he used to build his own amps. I can state unequivocally that the components supplied in this current round of kits, at least at these critical points, is below the quality required to achieve ultimate performance.

Peter and Uriah did an excellent job, and I will always be grateful for their considerable efforts to make this amp available again and do such a thorough job of organizing the kits.
...
These are $65 amplifiers as supplied, but they gain in value completely out of proportion to the cost of a few simple improvements.

I couldn't agree more

Tonight I did a listening session with my brother (he's a musician and he knows well how music should sound) swapping components and apart confirming what both Tom and I think about C9/C21 he confirmed also some additional findings:

- C17,C18 must be pulled out: soundstage becomes wider and deeper (tryed both AVXs and Wimas)
- C19,C20 must be pulled out too: with both AVXs and Wimas (Wimas are better) sound is somewhat compressed, without there's a lot more air and sound is 'free'
- C6,C11: swapped with Silmics II 100uF 35V (they fit perfectly) another veil disappear and bass gains authority, is even deeper and more articulated.

Mauro's original design doesn't have C17,C18,C19,C20.

At first Silmics in C6,C11 are horrible they must burn-in for 20-40 hours.

For C6, C11 positions I've ordered Nichicon KZ and Nichicon FG for C1,C2 for the next caps tryout.

Quote:

Originally posted by udailey We stuck with the BOM and let it be affordable to all. A 50 cent cap makes it affordable to all and an AudioCap Theta by itself would probably have taken away the affordability.
I bought some BlackGates yesterday by the way. I know caps count

And you both did a great job!

Uriah, if you want bass authority you must try Silmics in C9,C6,C11!!!

I think it's terrific that people experiment with these components and report it here. I for one am listening and trying to keep track before spending some extra money to try some of these out with a second kit (for honest to goodness blind comparison).

One thing that would be fun (not sure how to accomplish this) is to come up with a couple of upgrade recommendation lists. People posting personal impressions here is a valuable start, but it would be nice if we could somehow keep a running account of this. I am wary of people later being told "hey, there is this 1000 posts thread and you can find the info in there"...

What I am asking is this. Is there a way (maybe we can use the wiki?) to keep a running "count" of suggested modifications based on budget. If the sky is the limit you can do crazy things and clearly asymptotically it will be meaningless. Engineering design is all about: "If I have 1$ more to spend where should I spend it?"

So, with that in mind. Let's say: if I had 10$ to spend additional where should I spend them? What about 20$ (or 50$)? What about 100$ extra? (Beyond that I'll probably pass and consider other designs...)

BTW, it may be a fun exercise for someone who is so inclined to take the BOM and make their all out star kit (with prices!). If there is interest someone could put it together (not me; I want to do other things). I might get one just for the comparison fun.

Originally posted by udailey Dario, When you say to remove those caps.. Are you just pulling them from the board entirely? Are you subbing another part in or are you shorting it or leaving it open?
Uriah

I never soldered them, I was skeptical about Low ESR caps bypassing.

Next I've mounted some sockets so I could try them.

The comparison so was made without caps and with caps fitted in the sockets.

Don't short them!!! (shorting V+ and V- to ground it's not a great idea )

anyway... finally completed mono-blocs- and they work. I took time- and have (both) working w/out 'heat-sinks' ... on the 3886 chips. I don't listen loud, and could 'feel' ... the music on my thumb and (it does get hot)... but not so hot that I can't keep a finger on that 'chip'. I'll put a heatsink on it eventually- This is just to test it. I've got a 22 volt transformer- dual secondaries- no ground on this toroid transformer, but info about 'transformer hook-ups' ... helped me out. I see why the first cap into this amp can make a big difference... but am in no hurry to change anything- (until tomorrow).... thanks to all! - I encourage everyone to get it up and running just the way it is... then go for the (many) possible modifications/tweeks. thanks-

WHOA! I would not suggest to anyone to run these amps without a heatsink for any reason. The risk is simply too great, and the reward is zero.

Uriah and Peter, I did not mean to criticize your efforts in any way, but only to put the stock kits in relation to a modest outlay for some upgrades. Please accept my apolgy if you took offense.

Yes, I believe the original MyRef did not have bypass caps. There was quite a lot of debate and uncertainty about which version sounded better, and what values of bypass to use. This may come down to a personal preference. There are benefits to bypassing, but you may find it better without. The space is on the board because someone (Russ) thought it sounded better with the bypass caps. At least that mod is free.

I'm happy to see others reporting success! We all want to learn about your various experiments with parts selection and enclosures.

The mods or substitutions I described are not ambiguously beneficial. Cost is always a factor, but why take the time and trouble to build a compromise when a truly incremental increase in cost yields disproportionate benefits? Dario and I are willing to experiment and describe the results so all of you don't have to go through the same learning curve, unless you're eager to learn for yourselves. You can rest assured that the changes we describe are for the better, and some are not at all subtle.

Yikes, do we already need another MyRef thread to document the cost/benefit ratios?